In a conventional crawler structure of a crawler type work vehicle, a traveling crawler belt is formed of crawler belt links wound endlessly between a sprocket and an idler that are disposed in respective rear and front positions of a main frame. This crawler belt is held by a plurality of track rollers on a ground-contact side, is held by carrier rollers on a non-ground-contact side to maintain uniform tension and is driven by being wound around a sprocket member of the sprocket.
In such a crawler structure, when a tread of the crawler belt link is in rolling contact with the track roller, the carrier roller or the idler during travel, the tread wears down unevenly, thus showing corrugated wear. Such uneven wear is caused, for example, during travel on soft ground G as shown in FIG. 13(a). Since soft ground G easily causes sinking, earth and sand easily adhere to the crawler belt. The earth and sand adhere between tread 51 of crawler belt link 50 and idler 55, thus causing the wear when tread 51 slides in surface D of contact with idler 55. Moreover, as shown in FIG. 13(b), when ground G is soft enough to easily cause sinking as in the above case, the earth and sand adhere to respective ends of treads 51 of crawler belt links 50 at track roller 56, thus causing the wear during slide. Briefly speaking, traveling on the soft ground quite often causes the part contacting idler 55 or track roller 56 to show severe partial wear because crawler belt 52 sinks easily, and consequently, tread 51 of crawler belt link 50 shows corrugated wear 53 as illustrated in FIG. 13(c). A high degree of corrugated wear results in vibration of a vehicle body during travel on a stable hard road, and when the corrugated wear becomes noticeable, noise is caused, thus adversely affecting an environment. Accordingly, the link must be replaced when tread 51 of crawler belt link 50 shows the severe corrugated wear, and such replacement reduces cost efficiency.
For solving the problem of wear of the crawler belt link, no concrete means is proposed. A known measure against the wear of the crawler belt link is disclosed, for example, in Japanese Utility Model Unexamined Publication No. H01-125286. According to this publication, a flange of the track roller is ground according to wear of the tread of a track link (crawler belt link) at the track roller. The flange is thus prevented from contacting a connecting pin boss of the track link, whereby the use of the crawler belt link is extended.
However, the measure disclosed in Japanese Utility Model Unexamined Publication No. H01-125286 is not a technique adapted to solve the problem that is addressed by the present invention because this measure is based on the assumption that the link shows overall wear. This measure solves problem that only the initial flange maintains its size as a result of the tread showing the wear at the roller where relative wear is caused, by grinding the flange according to the wear of the tread. As described earlier, no measure against the corrugated wear or uneven wear of the crawler belt link is found, so that there is no other choice but to replace the link. Accordingly, the reduction of running costs remains unattained under present circumstances.
In view of such circumstances, the present invention aims to provide a crawler belt link grinding system and a crawler structure including the grinding system that allow a tread to withstand long-term use by normalizing, with operation continuing, the tread through grinding in an early stage where uneven wear such as corrugated wear occurs.